PROJECT SUMMARY The long-term goal of our HeartMap Dynamic Automated External Defibrillator Registry (AED Registry) is to ensure safety of AEDs by performing postmarket surveillance. AEDs are used to treat out-of-hospital cardiac arrest (OHCA). Each major AEDD manufacturer has recalled their devices to address one or more potential safety issues. Challenges with surveillance of AEDs are typical of challenges with surveillance of other medical devices. They are mobile in space and time, as they are distributed in locations anticipated to be close to the scene of cardiac arrest and moved periodically from one location to another. They are ubiquitous, as there are 1.2 million pre-existing devices, and about 180,000 new devices installed annually. Importantly, there is no widely deployed method of tracking their location and use in community settings. As well, monitoring the outcome of every AED use is necessary to identify those uses that may have caused or contributed to a death, since the majority of patients treated for OHCA die. This study will maintain a dynamic registry for surveillance of AED location and use so as to implement and maintain a national AED surveillance system. Recently we developed and pilot tested a methodology to tag AEDs with a Unique Device Identifier (UDI). According to this method, AEDs are tagged with a UDI that consists of two-dimensional matrix code (QR code, Denso Wave Inc., Chita-gun, Japan); then the UDI as well as the location and status of the device are recorded using open-source software native to contemporary smartphones and this information is passed to a database in real time via the internet (Non-Provisional Patent # 61/498,424). The device-specific information in the database is updated dynamically by rescanning the UDI after each use of the AED. We have applied UDIs to AEDs in Philadelphia, PA and Seattle, WA.(FDA 1U01FD004587-01, Nichol, PI). Importantly, we have leveraged this cooperative agreement with FDA to develop and implement ongoing collaborations with and fiscal support from AED monitor/defibrillator manufacturers. We have linked our AED Registry to EMS process and outcome benchmarking data available from the Resuscitation Outcomes Consortium in a simple EMS registry to incent EMS agencies to participate in the AED Registry. Our primary aim is to provide reliable, valid and sustainable postmarket surveillance of AEDs using UDI, smartphones and citizen engagement via crowdsourcing. We anticipate by study end an annual catchment population of at least 20 million individuals, at least 11,192 AEDs with UDIs in public locations, at least 16,020 EMS-treated OHCA, and 2.5% of OHCA are treated with an AED by a layperson. If 80% of AEDs are known at one year, there will be precision of 1.0% in the estimate of AED readiness for use, and 2.9% in the estimate of survival to discharge associated with AED use.